It is well known that ascorbic acid (or Vitamin C as it is synonomously referred to herein) is essential to the maintenance of a healthy and attractive skin appearance in humans. Vitamin C helps to stimulate and regulate the production of collagen in human skin tissue thus retarding the formation of wrinkles and otherwise helping to avoid a prematurely aged look to skin which, in turn, helps to maintain a healthier and younger looking appearance longer. Vitamin C also acts to help prevent or minimize lipid oxidation and other forms of cellular damage resulting from prolonged exposure to the sun's ultraviolet rays, further counteracting premature aging of the skin. It is believed further still that ascorbic acid helps to inhibit (i) the formation of melanin which leads to skin discoloration during the aging process, and (ii) the release of histamine from cellular membranes believed to be responsible for many allergenic reactions, particularly among individuals having so-called sensitive skin.
Because of these many beneficial effects, it has long been a desirable objective to percutaneously deliver effective concentrations of ascorbic acid directly to the skin's underlying tissue matrix (i.e. the dermal layer) via a topically applied, cosmetically elegant carrier or base. Although ascorbic acid is readily soluble in water, it oxidizes rapidly in aqueous solutions, and thus cannot be stabilized in sufficient concentration in such media to achieve skin appearance enhancement effects. Solubility of ascorbic acid in non-aqueous media on the other hand is quite limited, thereby preventing an anhydrous base from achieving the desired level of stability and therefore, efficacy For these reasons, unstabilized ascorbic acid heretofore has been used in cosmetic formulas only in trace amounts of less than about 0.1% by weight to serve as an antioxidant, and prior attempts to develop and market an acceptable cosmetic formulation containing efficacious concentrations of stabilized ascorbic acid have failed.